The present invention relates to a paddle latch for a closure. Particularly, although not exclusively, the present invention concerns paddle latches designed to be installed on the doors of heavy plant containers and buildings where water ingress to the interior of the container or building is undesirable.
It is known to provide paddle latches on the doors of heavy plant containers or buildings containing heavy plant equipment such as generators or pumps. Paddle latches are suited to this application as paddles generally provide a large area with which to actuate the latch, which can be advantageous if the user is wearing protective gloves. Furthermore, the paddle latch acts as a latch and handle whereby the user only needs to pull on the paddle to both actuate the latch and open the door in the same movement.
Paddle latches often comprise a latch member which, when in a latched condition, engages with a feature on the door frame such that the door cannot be opened. The latch member is often mounted on a shaft such that it can rotate from a latched position whereby it engages the feature on the door frame to an unlatched position whereby it is clear of that feature and the door can be opened.
In known paddle latches, the latch member is often resiliently biased towards the latched position. Unlatching can be achieved by actuating the paddle which physically contacts the latch member overcoming the resilient bias and moving the latch member into an unlatched position whereby the door may be opened. It is also known for the interaction between the paddle and the latch member to only act to move the latch member into an unlatched position. Therefore when the paddle is in the closed position, movement of the latch member will not cause corresponding movement of the paddle. Consequently, the door can be closed and latched without any corresponding motion of the paddle. This is desirable as it is instinctive to apply a door closing force upon the paddle, and if it was to move in an opposite sense to the applied force, this movement would create both undue stresses on the components of the latch and would make closing the door more difficult.
In order to provide a slam function that allows the door to be shut without corresponding movement of the paddle, previous paddle latches have provided a mechanical interaction between the paddle and the latch member that is only effective in a single direction, such that movement of the paddle actuates the latch member from a latched to an unlatched position (in order to open the door), but movement of the latch member from a latched position to an unlatched position and back again (e.g. during door closure) does not cause corresponding motion of the paddle.
It is generally undesirable to allow water ingress into the container or building in which the equipment is stored. Heavy plant equipment such as generators and transformers do not respond well to the presence of water, and regulations stipulating levels of sealing on the containers or buildings are becoming ever more stringent. Water ingress can not only impair the operation of this equipment, but can also cause corrosion of metals. Furthermore, water can collect in sumps provided under such equipment, reducing their capacity for collecting oil, and resulting in oil over-flowing into the surrounding environment.
Items of heavy plant equipment such as generators often create a negative pressure environment inside the container or building as they operate, which results in a “suction” effect at any orifices between the exterior and the interior of a container or building. This suction effect draws in any water that may be present on the surface of the container or building resulting from rain fall or condensation.
Furthermore, items of heavy plant equipment (such as generators) often create a lot of noise. Any such noise can be transmitted from the interior to the exterior of the container via orifices and slots in latches. This noise can be disruptive, and cause discomfort to those in the vicinity of the container. It is therefore desirable to decrease the noise transmitted from the interior to the exterior of the container.
As discussed above, known paddle latches require that the paddle (normally located on the exterior of the building for access) and the latch member (normally located on the interior of the building such that it can contact a part of the door frame) have to be in contact in order for the latch to operate. The requirement for a mechanical interaction implies that there must be some kind of orifice or slot through which one of the components must pass in order to interact with the other. Furthermore, due to the motion of the components the orifice or slot is usually at least partially open in order to allow linear movement during operation.
Bearing in mind the requirement for sealing discussed above, the existence of such slots and orifices is disadvantageous in paddle latches.